Revert "VM: Fix memory leaks during isolate spawning"

runtime/vm/snapshot.cc

Index: runtime/vm/snapshot.cc
diff --git a/runtime/vm/snapshot.cc b/runtime/vm/snapshot.cc
index 669df78bd8ba604dba9ff5513e52cc7db4df7f35..cb9dfde5778a5b8fd62413cb0c0d9ad33d04f408 100644
--- a/runtime/vm/snapshot.cc
+++ b/runtime/vm/snapshot.cc
@@ -1908,8 +1908,7 @@ void SnapshotWriterVisitor::VisitPointers(RawObject** first, RawObject** last) {
 MessageWriter::MessageWriter(uint8_t** buffer,
                              ReAlloc alloc,
                              DeAlloc dealloc,
-                             bool can_send_any_object,
-                             intptr_t* buffer_len)
+                             bool can_send_any_object)
     : SnapshotWriter(Thread::Current(),
                      Snapshot::kMessage,
                      buffer,
@@ -1918,8 +1917,7 @@ MessageWriter::MessageWriter(uint8_t** buffer,
                      kInitialSize,
                      &forward_list_,
                      can_send_any_object),
-      forward_list_(thread(), kMaxPredefinedObjectIds),
-      buffer_len_(buffer_len) {
+      forward_list_(thread(), kMaxPredefinedObjectIds) {
   ASSERT(buffer != NULL);
   ASSERT(alloc != NULL);
 }
@@ -1935,9 +1933,6 @@ void MessageWriter::WriteMessage(const Object& obj) {
   if (setjmp(*jump.Set()) == 0) {
     NoSafepointScope no_safepoint;
     WriteObject(obj.raw());
-    if (buffer_len_ != NULL) {
-      *buffer_len_ = BytesWritten();
-    }
   } else {
     FreeBuffer();
     ThrowException(exception_type(), exception_msg());